A key part of learning to speak with others is figuring out when to start talking and how to hold the floor in conversation. For young children, the challenge of planning a linguistic response can slow down their response latencies, making misunderstanding, repair, and loss of the floor more likely. Like adults, children can mitigate their delays by using fillers (e.g., <i>uh</i> and <i>um</i>) at the start of their turns. In this chapter I analyze the onset and development of fillers in five children&#8217;s spontaneous speech from ages 1;6&#8211;3;6. My findings suggest that children start using fillers by 2;0, and use them to effectively mitigate delay in making a response.